Mixed infection assays. A- Qualitative assay. Aggregative C. freundii (EACF) strain 205 improves bacterial adhesion when in combination with typical EAEC strains. B- Quantitative mixed infection assay. Adherence to HeLa cells displayed by EACF 205 and EAEC strains in mixed infections assays was quantified using the counting of colony-forming units (CFU), and was compared with adhesion displayed by the monocultures. EAEC strains showed antagonistic behaviors when in presence of EACF 205. a denotes P < 0.05 for comparison of 2 groups; b and c P < 0.001. Statistical analyses: independent-sample T test.